Infections of the oral cavity, such as of the tissue supporting teeth, are a common problem in mammals, including humans. Oral cavity infections range from caries development, arising from dental plaque bacterial damage to hard tooth tissue, to halitosis, arising from the volatile sulfur compounds (VSCs) produced by bacterial metabolic degradation of organic substances, to gingivitis, the inflammation of the gingiva (i.e., gum tissue) caused by dental plaque, which can progress to periodontis, a family of inflammatory diseases of periodontium. Dental plaque, which is a biofilm, is generally discussed in U.S. Pat. No. 7,497,834. Microorganisms and oral cavity infections are generally discussed in U.S. Publication No. 2009/0016973. Untreated periodontal infections can result in the progressive destruction of alveolar bone, leading to loss of teeth. Furthermore, oral health may be indicative of systemic health (Kim et al., 2006, Odontology 94:10-21). Treatment of oral infection may contribute to ameliorating systemic disease.
Current prophylactic and therapeutic treatments for oral tissue infections include brushing, flossing, topical fluoride, scaling and root planing, antiseptic mouth rinse, such as with a peroxide, antibiotics and, in extreme cases, surgical excision of infected tissue. Chlorine dioxide is known to be a disinfectant, as well as a strong oxidizing agent. The bactericidal, algaecidal, fungicidal, bleaching, and deodorizing properties of chlorine dioxide are also well known. Therapeutic and cosmetic applications for chlorine dioxide are known. For example, U.S. Publication No. 2009/0016973 describes the use of stabilized chlorine dioxide solutions for the prevention of oral disease. U.S. Pat. No. 5,281,412 describes chlorite and chlorine dioxide compositions that provide antiplaque and antigingivitis benefits without staining the teeth.
The traditional method for preparing chlorine dioxide involves reacting sodium chlorite with gaseous chlorine (Cl2(g)), hypochlorous acid (HOCl), or hydrochloric acid (HCl). The reactions proceed at much greater rates in acidic medium, so substantially all traditional chlorine dioxide generation chemistry results in an acidic product solution having a pH below 3.5. Chlorine dioxide may also be prepared from chlorate anion by either acidification or a combination of acidification and reduction. At ambient conditions, all reactions require strongly acidic conditions; most commonly in the range of 7-9 N. Heating of the reagents to higher temperature and continuous removal of chlorine dioxide from the product solution can reduce the acidity needed to less than 1 N.
A method of preparing chlorine dioxide in situ uses a solution referred to as “stabilized chlorine dioxide.” Stabilized chlorine dioxide solutions contain little or no chlorine dioxide, but rather, consist substantially of sodium chlorite at neutral or slightly alkaline pH. Addition of an acid to the sodium chlorite solution activates the sodium chlorite, and chlorine dioxide is generated in situ in the solution. The resulting solution is acidic. Typically, the extent of sodium chlorite conversion to chlorine dioxide is low, and a substantial quantity of sodium chlorite remains in the solution.
The current literature summarized above describes the use of chlorine dioxide compositions and methods that are damaging to biological tissues, including soft tissues such as gums and hard tissues such as tooth enamel and dentin. Methods, compositions, devices and systems for using chlorine dioxide for treatment of oral infection in which biological tissue is not damaged are needed.